A Schottky diode with polarized junction and dual anode structure and its preparation method and application

Abstract

The present invention relates to a Schottky diode with a polarization junction and a dual-anode structure, as well as a preparation method and applications. The Schottky diode comprises a substrate, an epitaxial layer and an electrode. The epitaxial layer comprises a buffer layer, a GaN channel layer, an AlGaN barrier layer and a polarization junction stacked in sequence. The polarization junction consists of a lightly doped p-GaN layer and a heavily doped p-GaN layer. An ohmic anode is provided on the surface of the polarization junction. Anode grooves and cathode grooves are provided on both sides of the epitaxial layer. The grooves extend along the surface of the polarization junction to a certain depth in the AlGaN barrier layer. A low-work-function Schottky anode and a high-work-function Schottky anode are provided in the anode grooves, and an ohmic cathode is provided in the cathode grooves. The present invention combines the polarization junction structure with the dual-anode structure, so that the forward and reverse characteristics of the device are well balanced, the electric field inside the device is redistributed, the breakdown voltage is increased, the turn-on voltage and on-resistance are reduced, and leakage current is suppressed.

Description

Technical Field

[0001] The present invention relates to the field of microelectronic technology, in particular to a Schottky diode with a polarized junction and a double anode structure, and a preparation method and application thereof. Background Art

[0002] Power devices are semiconductor devices capable of carrying high currents and withstanding high voltages. They primarily perform energy conversion, signal amplification, and switch control functions in circuits. Gallium nitride (GaN), a third-generation semiconductor with excellent physical and chemical properties, features a wide bandgap, high carrier mobility, high thermal conductivity, and a large critical breakdown electric field. It also exhibits excellent stability in extreme environments, making it an ideal material for power devices. Schottky diodes (SBDs), a type of power diode, are based on a Schottky barrier formed by metal and semiconductor. They utilize majority carriers for conduction, lack carrier storage, and offer high switching speeds and minimal switching losses, making them suitable for microwave and high-speed applications. Due to their high mobility and high concentration of two-dimensional electron gas (2DEG), lateral Schottky diodes fabricated using AlGaN / GaN heterojunctions often exhibit low turn-on voltage and on-resistance, making them widely used in rectifier circuits, inverters, and 5G communications. However, current AlGaN / GaN Schottky diodes still suffer from high turn-on voltage, high on-resistance, and low breakdown voltage. Summary of the Invention

[0003] In view of the technical problems existing in the prior art, the primary purpose of the present invention is to provide a Schottky diode with a polarized junction and a dual anode structure having a high breakdown voltage and a low turn-on voltage and a preparation method thereof.

[0004] The present invention adopts at least the following technical solutions:

[0005] In one aspect, the present invention provides a Schottky diode with a polarized junction and a double anode structure, comprising an epitaxial layer and an electrode disposed on a substrate;

[0006] The epitaxial layer includes a buffer layer, a GaN channel layer, an AlGaN barrier layer, and a polarization junction stacked in sequence; the polarization junction is formed by stacking a lightly doped p-GaN layer and a heavily doped p-GaN layer, the lightly doped p-GaN layer is in contact with the AlGaN barrier layer, and an anode groove and a cathode groove are provided on both sides of the epitaxial layer, and the grooves extend along the surface of the epitaxial layer to a certain depth in the AlGaN barrier layer;

[0007] The electrodes include a low work function Schottky anode, a high work function Schottky anode, an ohmic anode, and an ohmic cathode. The low work function Schottky anode and the high work function Schottky anode are arranged in the anode groove and in contact with the AlGaN barrier layer. The ohmic anode is located on the polarization junction. The high work function Schottky anode covers the low work function Schottky anode and extends to the surface of the ohmic anode. The ohmic cathode is arranged in the cathode groove and in contact with the AlGaN barrier layer. A passivation layer is provided between the high work function Schottky anode, the ohmic anode, and the ohmic cathode. The passivation layer is also located between the polarization junction and the ohmic cathode.

[0008] The ratio of the contact area between the low work function Schottky anode and the barrier layer to the total contact area between the low work function Schottky anode, the high work function Schottky anode and the barrier layer is between 0.2 and 0.8.

[0009] Preferably, the ratio of the contact area between the low work function Schottky anode and the barrier layer to the total contact area between the low work function Schottky anode, the high work function Schottky anode and the barrier layer is 0.5.

[0010] Preferably, the doping concentration of the heavily doped p-GaN layer is 1×10 18 cm -3 ~1×10 21 cm -3 , with a thickness of 10 nm to 50 nm; the doping concentration of the lightly doped p-GaN layer is 1×10 14 cm -3 ~1×10 17 cm -3 , and its thickness is 5nm~30nm.

[0011] Preferably, the width of the polarization junction is 4 μm to 10 μm;

[0012] The total width of the low-work-function Schottky anode and the high-work-function Schottky anode in contact with the barrier layer is 4 μm.

[0013] Preferably, the material of the ohmic cathode is selected from one of Ti, Al, W and Mo; the material of the low work function Schottky anode is selected from one of Ti, Al, W and Mo; the material of the high work function Schottky anode and the ohmic anode is selected from one of Ni, Pt, Au and Pd.

[0014] Preferably, the buffer layer is one of carbon-doped high-resistance GaN, AlN, and AlGaN, and its thickness is 1μm to 5μm; the thickness of the GaN channel layer is 0.1μm to 1μm; the AlGaN barrier layer has an Al component of 0.2 to 0.3 and its thickness is 10nm to 60nm.

[0015] Preferably, an AlN insertion layer is provided between the barrier layer and the GaN channel layer, and the thickness of the AlN insertion layer is 1 nm;

[0016] The substrate is one of a sapphire substrate, a Si substrate, a SiC substrate and a GaN single crystal substrate.

[0017] Preferably, the passivation layer is made of SiN X , one of Al2O3, SiO2, ZrO2 and HfO2.

[0018] In one aspect, the present invention further provides a method for preparing a Schottky diode having a polarized junction and a dual-anode structure, comprising the following steps:

[0019] A buffer layer, a GaN channel layer, an AlGaN barrier layer, a lightly doped p-GaN layer, and a heavily doped p-GaN layer are sequentially grown on the substrate to form an epitaxial stack;

[0020] defining an active area, etching the epitaxial stack to a certain depth in the AlGaN barrier layer, retaining a portion of the AlGaN barrier layer, and forming an anode groove and a cathode groove;

[0021] defining an ohmic cathode region and depositing an ohmic contact metal layer to form an ohmic cathode;

[0022] defining an ohmic anode region and forming an ohmic anode on the heavily doped p-GaN layer;

[0023] defining a low work function Schottky anode region, and forming a low work function Schottky anode on the AlGaN barrier layer;

[0024] defining a high work function Schottky anode region, forming a high work function Schottky anode on the AlGaN barrier layer, wherein the high work function Schottky anode covers the low work function Schottky anode and extends to the surface of the ohmic anode;

[0025] Depositing a passivation layer between the anode and the cathode, the passivation layer also covering between the polarization junction and the ohmic cathode;

[0026] The ratio of the contact area between the low work function Schottky anode and the barrier layer to the total contact area between the low work function Schottky anode, the high work function Schottky anode and the barrier layer is between 0.2 and 0.8.

[0027] Preferably, carbon is doped into the buffer layer during the growth process to form a high-resistance GaN buffer layer;

[0028] In the step of forming the anode groove and the cathode groove, the epitaxial layer is etched using a low-damage ICP process.

[0029] The above-mentioned Schottky diodes are used in electronic products.

[0030] Compared with the prior art, the present invention has at least the following beneficial effects:

[0031] The present invention achieves a good balance between the forward and reverse characteristics of the device through the arrangement of the polarization junction and the double anode. The polarization junction forms a GaN / AlGaN / GaN double heterojunction with the AlGaN barrier layer and the GaN channel layer. The interface of the GaN / AlGaN heterojunction generates a two-dimensional hole gas (2DHG), and the interface of the AlGaN / GaN heterojunction generates a 2DEG. Under high reverse bias, the fixed positive and negative charges achieve a balance by compensating each other, so that the channel electric field is evenly distributed, and the electric field peak is transferred from the edge of the Schottky anode to the edge of the polarization junction. The edge avoids the electric field concentration at the Schottky anode position and weakens the adverse effect of the reduced Schottky barrier height brought by the double anode on the reverse characteristics; at the same time, in order to reduce the turn-on voltage and on-resistance, through the introduction of the double anode, the low work function Schottky anode is turned on first under low forward bias, which reduces the turn-on voltage of the device. After the bias voltage is increased, the high work function Schottky anode is turned on, and the double anodes participate in conduction together. The current mainly flows into the low work function Schottky anode, reducing the on-resistance and weakening the adverse effect of the reduced 2DEG surface concentration brought by the polarization junction on the forward characteristics. In the dual-anode structure, the ratio of the contact area between the low-work-function Schottky anode and the AlGaN barrier layer to the total contact area between the low-work-function Schottky anode, the high-work-function Schottky anode and the AlGaN barrier layer is between 0.2 and 0.8. The optimization of this area further balances the forward and reverse characteristics. In particular, when the contact areas between the low-work-function Schottky anode and the high-work-function Schottky anode and the AlGaN barrier layer are equal, the device's breakdown voltage is effectively increased, while the turn-on voltage and leakage current are reduced.

[0032] The present invention partially etches the AlGaN barrier layer, so that the electrode penetrates into the AlGaN barrier layer, better contacts the 2DEG, further reduces the turn-on voltage, and the setting process has little impact on the channel. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of a Schottky diode structure with a polarized junction and a dual anode structure according to an embodiment of the present invention.

[0034] Figure 2Schematic diagram of the structure of the AlGaN / GaN Schottky diode in comparative example 1.

[0035] Figure 3 Schematic diagram of the structure of the polarization junction single anode AlGaN / GaN Schottky diode in comparative example 2.

[0036] Figure 4 for Figures 1 to 3 Comparison of forward IV characteristic curves of Schottky diodes.

[0037] Figure 5 for Figures 1 to 3 Comparison of breakdown voltage curves of Schottky diodes. DETAILED DESCRIPTION

[0038] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings of the present invention. The described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, other embodiments obtained by ordinary technicians in this field without making creative work are all within the scope of protection of the present invention. The experimental methods described in the following examples are all conventional methods unless otherwise specified; the reagents and materials, unless otherwise specified, can be obtained from public commercial channels.

[0039] Spatially relative terms such as "below," "beneath," "below," "above," "upper," etc. are used in this specification to explain the positioning of one element relative to a second element. These terms are intended to encompass different orientations of the device in addition to different orientations than those depicted in the figures.

[0040] In addition, the use of terms such as "first," "second," and the like to describe various elements, layers, regions, sections, and the like is not intended to be limiting. The use of "having," "containing," "including," and "comprising" are open-ended terms that indicate the presence of stated elements or features, but do not exclude additional elements or features, unless the context clearly indicates otherwise.

[0041] The width in the present specification refers to the direction between the anode and the cathode.

[0042] like Figure 1 As shown, an embodiment of the present invention provides a Schottky diode with a polarized junction and a double anode structure, which includes an epitaxial layer and electrodes arranged on a substrate 1.

[0043] The substrate 1 is selected from the group consisting of a sapphire substrate, a Si substrate, a SiC substrate, and a GaN single crystal substrate. The epitaxial layer comprises a buffer layer 2, a GaN channel layer 3, an AlGaN barrier layer 4, and a polarization junction 5 stacked in sequence. The buffer layer 2 is selected from the group consisting of carbon-doped high-resistance GaN, AlN, and AlGaN, and has a thickness of 1 μm to 5 μm. In a preferred embodiment, the buffer layer 2 is a carbon-doped high-resistance GaN layer. The GaN channel layer 3 has a thickness of 0.1 μm to 1 μm. The AlGaN barrier layer 4 has an Al content of 0.2 to 0.3 and a thickness of 10 nm to 60 nm.

[0044] In a preferred embodiment, an AlN insertion layer is provided between the AlGaN barrier layer and the GaN channel layer, and the thickness of the AlN insertion layer is 1 nm.

[0045] The polarization junction 5 is formed by stacking a lightly doped p-GaN layer and a heavily doped p-GaN layer. The lightly doped p-GaN layer is in contact with the AlGaN barrier layer. The doping concentration of the lightly doped p-GaN layer is 1×10 14 cm -3 ~1×10 17 cm -3 The thickness is 5nm to 30nm. The doping concentration of the heavily doped p-GaN layer is 1×10 18 cm -3 ~1×10 21 cm -3 , thickness is 10nm~50nm.

[0046] The epitaxial layer is provided with an anode groove and a cathode groove, which extend along the surface of the polarization junction to a certain depth in the barrier layer. The thickness of the remaining AlGaN barrier layer in the anode groove area and the cathode groove area is 5nm to 20nm.

[0047] The electrodes include a low-work-function Schottky anode 7, a high-work-function Schottky anode 8, an ohmic anode 9, and an ohmic cathode 6. The low-work-function Schottky anode 7 and the high-work-function Schottky anode 8 are disposed in the anode recess region and contact the AlGaN barrier layer 4. The ohmic anode 9 is disposed on the surface of the polarization junction 5. The high-work-function Schottky anode 8 covers the low-work-function Schottky anode 7 and extends to the surface of the ohmic anode 9. The ratio of the area of ​​contact between the low-work-function Schottky anode and the AlGaN barrier layer to the total area of ​​contact between the low-work-function Schottky anode, the high-work-function Schottky anode, and the AlGaN barrier layer is between 0.2 and 0.8. In a preferred embodiment, the ratio of the area of ​​contact between the low-work-function Schottky anode and the AlGaN barrier layer to the total area of ​​contact between the low-work-function Schottky anode, the high-work-function Schottky anode, and the AlGaN barrier layer is 0.5. The low-work-function Schottky anode forms a low Schottky barrier, which helps to obtain a low turn-on voltage and on-resistance. Combined with the setting of the high-work-function Schottky anode, the depletion region formed by the high Schottky barrier suppresses leakage current, compensating for the defects of the low-work-function Schottky anode. At the same time, through the setting of the polarized junction structure, the electric field peak is transferred to the edge of the polarized junction, reducing the electric field peak at the edge of the anode, avoiding electric field concentration at the edge of the anode, and reducing the adverse effect of the reduced Schottky barrier height caused by the dual anode on the breakdown voltage. The present invention achieves a better balance between the forward and reverse characteristics of the device through the interaction between the polarized junction and the dual anode structure.

[0048] The ohmic cathode is located in the cathode recess and contacts the AlGaN barrier layer. The ohmic cathode is made of one of Ti, Al, W, and Mo. The low-work-function Schottky anode is made of one of Ti, Al, W, and Mo. The high-work-function Schottky anode and ohmic anode are made of one of Ni, Pt, Au, and Pd.

[0049] The passivation layer 10 is arranged between the high work function Schottky anode, the ohmic anode and the ohmic cathode. The passivation layer 10 is also arranged in the cathode groove to isolate the polarization junction from the ohmic cathode. The passivation layer is made of SiN X , one of Al2O3, SiO2, ZrO2 and HfO2.

[0050] In one embodiment, the width of the polarization junction is 4 μm to 10 μm. In a preferred embodiment, the total width of the high work function Schottky anode and the low work function Schottky anode region is 4 μm, and the width of the low work function Schottky anode region is 2 μm.

[0051] Figure 2The AlGaN / GaN Schottky diode provided in Comparative Example 1 comprises a substrate 1, a GaN buffer layer 2, a GaN channel layer 3, an AlGaN barrier layer 4, and a passivation layer 10 stacked in sequence. It also includes an ohmic cathode 6 and a Schottky anode 8. The ohmic cathode 6 is disposed on the partially etched AlGaN barrier layer 4, forming an ohmic contact with the AlGaN barrier layer. The Schottky anode 8 is disposed on the partially etched AlGaN barrier layer 4, forming a Schottky contact with the AlGaN barrier layer and extending to the surface of the passivation layer 10 to form a field plate. The thickness of the remaining AlGaN barrier layer after etching is 5nm to 20nm. The ohmic cathode 6 is a Ti / Al / Ni / Au metal stack with thicknesses of 200 / 1300 / 500 / 1500nm. The Schottky anode 8 and field plate regions are formed of a Ni / Au metal stack deposited by thermal evaporation, with thicknesses of 500nm and 1500nm.

[0052] Figure 3 This is a polarization junction single-anode AlGaN / GaN Schottky diode of Comparative Example 2, comprising an epitaxial layer and an electrode disposed on a substrate 1, wherein the epitaxial layer comprises a stacked GaN buffer layer 2, a GaN channel layer 3, an AlGaN barrier layer 4, and a polarization junction. The polarization junction 5 comprises a lightly doped p-GaN layer and a heavily doped p-GaN layer. The electrode comprises an ohmic cathode 6, an ohmic anode 9, and a Schottky anode 8. The anode groove and the cathode groove are disposed on both sides of the epitaxial layer, extending along the surface of the epitaxial layer to a certain depth in the AlGaN barrier layer. The ohmic cathode 6 is disposed in the cathode groove and forms an ohmic contact with the AlGaN barrier layer 4. The ohmic anode 9 is disposed on the surface of the polarization junction 5. The Schottky anode 8 is disposed in the anode groove and forms a Schottky contact with the AlGaN barrier layer 4, extending to the surface of the ohmic anode 9. A passivation layer 10 is disposed between the Schottky anode 8 and the ohmic cathode 6, and isolates the polarization junction 5 from the ohmic cathode 6.

[0053] Another aspect of the present invention provides a method for preparing the Schottky diode having the above-mentioned polarized junction and dual-anode structure, comprising the following steps:

[0054] (1) A GaN buffer layer, a GaN channel layer, an AlN insertion layer, an AlGaN barrier layer, a lightly doped p-GaN layer, and a heavily doped p-GaN layer are sequentially grown on a substrate using MOCVD technology.

[0055] (2) The sample was photolithographically processed to define the active area, and mesa isolation was achieved using ICP etching, using Cl2 and BCl3 gases with an etching depth of 300 nm.

[0056] (3) The active area sample was photolithographically processed to define the cathode groove area, and low-damage ICP etching was used to remove the p-GaN layer and part of the AlGaN barrier layer. The groove width was 4 μm, and the thickness of the remaining AlGaN barrier layer was 15 nm.

[0057] (4) The sample obtained in step (3) was subjected to photolithography to define the anode groove area. The p-GaN layer and part of the AlGaN barrier layer were removed using low-damage ICP etching. The groove width was 4 μm, and the thickness of the remaining AlGaN barrier layer was 20 nm. After the two etching steps were completed, the etching damage was repaired by annealing at 450°C in a N2 environment for 5 minutes.

[0058] (5) The sample obtained in step (4) is subjected to photolithography to define the ohmic cathode region, and a Ti / Al / Ni / Au metal stack is deposited by thermal evaporation. The thickness of the metal stack is 200 / 1300 / 500 / 1500 nm, and the width of the ohmic cathode is 1.5 μm. The photoresist is then stripped and annealed. The annealing is performed in a N2 environment at 850°C for 30 seconds to form an ohmic cathode.

[0059] (6) The sample obtained in step (5) is subjected to photolithography to define the ohmic anode region, and a Ni / Au metal stack is deposited by thermal evaporation. The thickness of the metal stack is 10 / 20 nm, and then the photoresist is stripped and annealed. The annealing is performed in a N2 environment at 400°C for 3 minutes to form an ohmic anode.

[0060] (7) The sample obtained in step (6) was subjected to photolithography to define the low work function Schottky anode region, and W metal was deposited by sputtering at a pressure of 3 mTorr, a power of 20 W, and a rate of The thickness of the metal is 40nm, and then the photoresist is stripped to form a low work function Schottky anode.

[0061] (8) The sample obtained in step (7) is subjected to photolithography to define a high work function Schottky anode region. A Ni / Au metal stack is deposited by thermal evaporation. The thickness of the metal stack is 500 / 1500 nm. The photoresist is then stripped and annealed to form a high work function Schottky anode. The annealing is performed in an N2 environment at 450°C for 3 minutes. In this embodiment, the low work function Schottky anode and the high work function Schottky anode have equal contact areas with the AlGaN barrier layer.

[0062] (9) Si3N4 is deposited between the cathode and the anode by PECVD technology to form a passivation layer, thus obtaining a polarized junction double anode Schottky diode.

[0063] In another embodiment, a lightly doped p-GaN layer is first formed by epitaxial growth, and then an etching process is performed according to the above-mentioned preparation method to form an electrode. Subsequently, an ion implantation process is performed on the lightly doped p-GaN layer to form a heavily doped p-GaN layer of a certain depth to form a polarization junction, and finally a passivation layer is deposited.

[0064] Figure 3 The first six steps of the preparation method of the polarized junction single anode AlGaN / GaN Schottky diode shown are the same as steps (1) to (6) in the above preparation method. (7) The sample obtained in step (6) is photolithographically processed to define the Schottky anode region. A Ni / Au metal stack is deposited by thermal evaporation. The thickness of the metal stack is 500 / 1500 nm. The photoresist is then stripped and annealed. The annealing is performed at 450°C in an N2 environment for 3 minutes to form a Schottky anode. (8) Si3N4 is deposited between the cathode and the anode by PECVD technology to form a passivation layer. Figure 3 Polarized junction single anode Schottky diode shown.

[0065] Figure 2 The AlGaN / GaN Schottky diode shown is fabricated as follows:

[0066] (1) GaN buffer layer, GaN channel layer, AlN insertion layer and AlGaN barrier layer are grown on the substrate in sequence by MOCVD technology.

[0067] (2) The sample was photolithographically processed to define the active area, and mesa isolation was achieved using ICP etching, using Cl2 and BCl3 gases, an etching time of 60s, and an etching depth of 150nm.

[0068] (3) Si3N4 was deposited by PECVD technology to form a passivation layer. A mixture of 5% silane, nitrogen and ammonia was used for deposition. The silane flow rate was 240 sccm, the ammonia flow rate was 50 sccm, the power was 60 W, the temperature was 220°C, and the passivation layer thickness was 40 nm.

[0069] (4) The sample obtained in step (3) is subjected to photolithography to define the ohmic cathode region. The Si3N4 passivation layer in the region is first removed by wet etching. The etchant used in the wet etching is a BOE solution. The etching time is 40s. Then, part of the AlGaN barrier layer in the region is removed by ICP etching. The thickness of the remaining AlGaN barrier layer is 15nm. Then, a Ti / Al / Ni / Au metal stack is deposited by thermal evaporation. The thickness of the metal stack is 200 / 1300 / 500 / 1500nm. Finally, the photoresist is stripped and annealed. The annealing is carried out in an N2 environment at 850°C for 30s to form an ohmic cathode.

[0070] (5) The sample obtained in step (4) is subjected to photolithography to define the Schottky anode groove area. The Si3N4 passivation layer in the area is first removed by wet etching. The etching solution used in the wet etching is BOE solution. The etching time is 40s. Then, part of the AlGaN barrier layer in the part of the area is removed by ICP etching. The thickness of the remaining AlGaN barrier layer is 20nm, forming a Schottky anode groove.

[0071] (6) The sample obtained in step (5) is subjected to photolithography to define the Schottky anode and field plate regions, and a Ni / Au metal stack is deposited by thermal evaporation. The thickness of the metal stack is 500 / 1500 nm, and then the photoresist is stripped and annealed. The annealing is carried out at 450°C in a N2 environment for 3 minutes to form a Schottky anode and field plate. Figure 2 The AlGaN / GaN Schottky diode shown.

[0072] Performance simulation test:

[0073] Depend on Figure 4 It can be seen that compared with the Schottky diodes of Comparative Examples 1 and 2, the turn-on voltage of the polarized junction dual-anode Schottky diode of the embodiment of the present invention is reduced by 54.29%. Figure 5 It can be seen that compared with the AlGaN / GaN Schottky diode structure of Comparative Example 1, the breakdown voltage of the polarized junction dual-anode Schottky diode of the embodiment of the present invention is increased by 164.71%. Compared with the polarized junction single-anode Schottky diode of Comparative Example 2, the breakdown voltage of the polarized junction dual-anode Schottky diode of the present invention is reduced by 4.16%.

[0074] By comparison with the comparative example, it can be clearly seen that the present invention reduces the influence of the dual anode structure on the breakdown voltage of the device, balances the forward and reverse characteristics of the device, effectively improves the breakdown voltage of the device, and reduces the turn-on voltage of the device through the setting of the polarization junction and the dual anode structure, and optimizes the setting of the ratio of low work function Schottky anode to high work function Schottky anode in the dual anode structure.

[0075] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A Schottky diode with a polarized junction and a double anode structure, characterized in that: comprising an epitaxial layer and an electrode disposed on a substrate; The epitaxial layer includes a buffer layer, a GaN channel layer, an AlGaN barrier layer, and a polarization junction stacked in sequence; the polarization junction is formed by stacking a lightly doped p-GaN layer and a heavily doped p-GaN layer, the lightly doped p-GaN layer is in contact with the AlGaN barrier layer, and an anode groove and a cathode groove are provided on both sides of the epitaxial layer, and the grooves extend along the surface of the epitaxial layer to a certain depth in the AlGaN barrier layer; The electrodes include a low work function Schottky anode, a high work function Schottky anode, an ohmic anode, and an ohmic cathode. The low work function Schottky anode and the high work function Schottky anode are arranged in the anode groove and in contact with the AlGaN barrier layer. The ohmic anode is located on the polarization junction. The high work function Schottky anode covers the low work function Schottky anode and extends to the surface of the ohmic anode. The ohmic cathode is arranged in the cathode groove and in contact with the AlGaN barrier layer. A passivation layer is provided between the high work function Schottky anode, the ohmic anode, and the ohmic cathode. The passivation layer is also located between the polarization junction and the ohmic cathode. The ratio of the contact area between the low work function Schottky anode and the barrier layer to the total contact area between the low work function Schottky anode, the high work function Schottky anode and the barrier layer is between 0.2 and 0.

8.

2. The Schottky diode according to claim 1, characterized in that The ratio of the contact area between the low-work-function Schottky anode and the barrier layer to the total contact area between the low-work-function Schottky anode, the high-work-function Schottky anode, and the barrier layer is 0.

5.

3. The Schottky diode according to claim 1 or 2, characterized in that: The doping concentration of the heavily doped p-GaN layer is 1×10 18 cm -3 ~1×10 21 cm -3 , with a thickness of 10 nm to 50 nm; the doping concentration of the lightly doped p-GaN layer is 1×10 14 cm -3 ~1×10 17 cm -3 , and its thickness is 5nm~30nm.

4. The Schottky diode according to claim 3, characterized in that: The width of the polarization junction is 4 μm to 10 μm; The total width of the low-work-function Schottky anode and the high-work-function Schottky anode in contact with the barrier layer is 4 μm.

5. The Schottky diode according to claim 1, 2 or 4, characterized in that: The material of the ohmic cathode is selected from one of Ti, Al, W and Mo; the material of the low work function Schottky anode is selected from one of Ti, Al, W and Mo; the material of the high work function Schottky anode and the ohmic anode is selected from one of Ni, Pt, Au and Pd.

6. The Schottky diode according to claim 5, characterized in that: The buffer layer is one of carbon-doped high-resistance GaN, AlN, and AlGaN, and its thickness is 1μm to 5μm; the thickness of the GaN channel layer is 0.1μm to 1μm; the Al component of the AlGaN barrier layer is 0.2 to 0.3, and its thickness is 10nm to 60nm.

7. The Schottky diode according to claim 1, 2, 4 or 6, characterized in that: An AlN insertion layer is provided between the barrier layer and the GaN channel layer, and the thickness of the AlN insertion layer is 1 nm; The substrate is one of a sapphire substrate, a Si substrate, a SiC substrate and a GaN single crystal substrate; The passivation layer is SiN X , one of Al2O3, SiO2, ZrO2 and HfO2.

8. A method for preparing a Schottky diode with a polarized junction and a double anode structure, characterized in that: The following steps are involved: A buffer layer, a GaN channel layer, an AlGaN barrier layer, a lightly doped p-GaN layer, and a heavily doped p-GaN layer are sequentially grown on the substrate to form an epitaxial stack; defining an active area, etching the epitaxial stack to a certain depth in the AlGaN barrier layer, retaining a portion of the AlGaN barrier layer, and forming an anode groove and a cathode groove; defining an ohmic cathode region and depositing an ohmic contact metal layer to form an ohmic cathode; defining an ohmic anode region and forming an ohmic anode on the heavily doped p-GaN layer; defining a low work function Schottky anode region, and forming a low work function Schottky anode on the AlGaN barrier layer; defining a high work function Schottky anode region, forming a high work function Schottky anode on the AlGaN barrier layer, wherein the high work function Schottky anode covers the low work function Schottky anode and extends to the surface of the ohmic anode; Depositing a passivation layer between the anode and the cathode, the passivation layer also covering between the polarization junction and the ohmic cathode; The ratio of the contact area between the low work function Schottky anode and the barrier layer to the total contact area between the low work function Schottky anode, the high work function Schottky anode and the barrier layer is between 0.2 and 0.

8.

9. The preparation method according to claim 8, characterized in that The buffer layer is doped with carbon during the growth process to form a high-resistance GaN buffer layer.

10. Use of the Schottky diode according to any one of claims 1 to 7 in electronic products.

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